Function binomial

crawl-ref/source/random.cc:391–399

Sample from a binomial distribution. * * This is the number of successes in a sequence of independent trials with * fixed probability. * * @param n_trials The number of trials. * @param trial_prob The numerator of the probability of success of each trial. * If greater than scale, the probability is 1.0. * @param scale The denominator of trial_prob, default 100. * @return

 * @return the number of successes, range [0, n_trials]
 */
int binomial(unsigned n_trials, unsigned trial_prob, unsigned scale)
{
    int count = 0;
    for (unsigned i = 0; i < n_trials; ++i)
        if (::x_chance_in_y(trial_prob, scale))
            count++;

    return count;
}

// range [0, 1.0)
// This uses a technique described by Saito and Matsumoto at